My personal opinion is there isn't anything specifically proprietary about it.
However, do you have an idea why they want it? My only concern is the
stylesheet defines Raleway fonts, which could be problematic if the
person who wants this uses it as-is: first, those fonts have a
license, which
Someone on the #solr IRC wants to obtain the PDF export stylesheet that
we use for publishing the reference guide as PDF.
I've managed to locate the stylesheet because apparently I do have the
necessary permission on Confluence, but I don't want to just give it to
them without making sure that we